There may be difficult situations where you need to bend you back. You must be very cautious about such situations. If it seems practically inevitable, you should adopt a posture such that you can transfer most of the weights to the stronger parts of your body, such as your arms. You may call this "supported bending'.

The stress on the back is much reduced by transferring the weight of your body and the load to your arm.

The weight of your body alone is sufficient to cause harm to your back in a bending posture. Supporting the weight of your body with your arm in such situations will certainly help preserving your back.